Concerned about possibile attacks against its nuclear sites by Israeli or U.S. forces, Iran has been trying to upgrade its air defense system in recent years, with limited success. While it has expanded its fiber-optic communications network and installed Chinese-built, automated command and control (C2) equipment, much of its air defense hardware dates from the 1970s. The U.S. built F-4 Phantom is still the mainstay of the Iranian Air Force, and the I-HAWK SAM system (purchased from the U.S. more than 30 years ago) remains the backbone of of Tehran's ground-based air defenses. Both are increasingly difficult to maintain, and obtaining spare parts is a major problem.
Reuters is reporting that Iran has negotiated a deal to buy the SA-15 mobile SAM system from Russia, for an undisclosed price. Designated the TOR-M1 by the Russians, the system provides advanced intercept capabilities against aircraft, cruise missiles and other standoff weapons, at short ranges. Iran reportedly plans to buy 29 SA-15s, which could substantially improve the point defenses at high value targets, including nuclear facilities.
There's only one problem with this report: we've heard these stories before. In recent years, there have been credible accounts that Iran was planning to purchase other Russian SAMs, most notably the long-range SA-10/SA-20 systems, with capabilities matching (and in some cases, exceeding) the U.S. built PATRIOT. But the Iranian deals never materialized, for a variety of reasons. Until the recent spike in oil prices, Tehran's defense budget was severely limited, with little room for high-priced acquisitions (a single SA-10 battery has a price tag of roughly $300 million). Increased oil revenues will permit more arms purchases, but there is still competition for resources within the Iranian military between the "regular" armed forces and the Revolutionary Guards.
Historically, the "regular" Air Force has been in charge of Iran's air defenses, but it has been viewed with suspicion by the political leadership, and fared relatively poorly in budget battles. More recently, the Revolutionary Guards Corps (IRGC) have organized their own air and air defense units, and they seem to be gaining the upper hand in the fight for military resources. If the SA-15s actually show up in Iran, they are likely to be an IRGC asset. However, that creates other problems for the Iranians, since cooperation between "regular" air defense units and their IRGC counterparts is minimal at best.
Finally, there's the issue of whether Iran will actually consummate the deal. Despite increase oil revenues, Tehran still prefers the "budget" route in defense matters, using the arms "gray" market to buy enough spares to keep their F-4s and I-HAWKs in operation, or refurbishing captured Iraqi aircraft to expand their air force. Acquisition of the SA-15 would be a significant upgrade for Iran, but there's a strong chance the deal struck in Moscow will never be finalized. We've heard these stories before, and more often than not, they simply don't pan out.